* Moved all code responsible for writing VMTs and interface wrappers (nobj.TVMTWriter, ncgutil.gen_intf_wrappers, ptype.write_persistent_type_info) into a new unit ncgvmt.pas. 
This improves compiling speed a bit (two iterations over symtables replaced by one, code generator is created once per unit rather than once per class).
In perspective it makes possible to reduce amount of generated smartlink sections and global labels.

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@24269 3ad0048d-3df7-0310-abae-a5850022a9f2